Plant azaleas in cool, partial shade in acidic, well-drained, organic soil, set the root ball a little high for drainage, and prune only after the flowers fade. Clemson says azaleas grow best in acid soil at pH 4.5 to 6.0, and Illinois Extension puts the target at “down towards pH 6”. UF/IFAS calls azaleas a classic Southern plant, for the structure they provide year-round and for the floral displays. Bloom times run from early spring to midsummer by species (Clemson).
- Sun
- Cool partial shade; dappled or filtered
- Origin
- Asia
- Soil
- Acidic, well drained, organic
- Soil pH
- 4.5–6.0 (Clemson); down towards 6 (Illinois)
- Bloom time
- Early spring to midsummer by species
- Prune
- After flowering
- Southern Indica cold limit
- About 20°F (UF/IFAS)
Sun and shade
Clemson says azaleas prefer cool, partially shaded sites, such as the filtered shade of pine trees. NC State says moist, well-drained, acidic soils in dappled shade. Clemson adds that azaleas exposed to full sun are more susceptible to lace bugs, so partial shade matters for that pest too.
Soil and pH
Soil pH is where the sources give slightly different targets.
Clemson
Illinois Extension
NC State
Taken together, the range is pH 4.5 to 6.0, and Illinois’s “down towards 6” sits at the top edge of Clemson’s range.
Planting and water
NC State says to plant the root ball high in the soil to help with drainage issues. It also says to avoid overwatering and over-fertilizing, and that the roots may rot if the soil does not drain well.
- Choose a shady, cool site. Partial shade, such as the filtered shade of pines (Clemson).
- Check the soil. Acidic, well drained and organic, pH 4.5 to 6.0 (Clemson).
- Plant the root ball high. This helps with drainage (NC State).
- Water carefully. Avoid overwatering; roots rot in soil that does not drain (NC State).
Feeding and pruning
Clemson says azaleas have low nutritional requirements compared to other shrubs, and to have a specific reason before fertilizing. NC State says pruning, if desired, may be done after flowering, and UF/IFAS says pruning can improve blooming and help azaleas develop into full, well-branched shrubs. Our azalea pruning guide covers the early July cutoff.
Cold hardiness
UF/IFAS says Southern Indica azaleas typically tolerate temperatures down to 20°F without serious damage.
Types of azalea
UF/IFAS names Southern Indica hybrids, such as ‘George Tabor’, and Clemson names Satsuki, Kurume and the Encore reblooming types. Clemson says the reblooming types offer blooms twice a year, in spring and again in fall.
| Variety | Best for | Group | Bloom | Notes |
|---|---|---|---|---|
| Southern Indica | Southern gardens | Hybrids such as 'George Tabor' | — | Tolerate about 20°F (UF/IFAS) |
| Satsuki | — | — | — | Named by Clemson |
| Kurume | — | — | — | Named by Clemson |
| Encore | Two bloom seasons | Reblooming | Spring and fall | Named by Clemson |
Common azalea problems
Grow these next
Soil pH matters for another shrub too: in our hydrangea guide, pH shifts the flower color. The lavender guide covers a shrub with very different needs, full sun and soil that drains perfectly. See the bloom calendar for how spring shrubs line up with the rest of the garden.
Frequently asked questions
What soil pH do azaleas need?
Clemson says azaleas grow best in acid soil, pH 4.5 to 6.0, that is well drained and organic. Illinois Extension says they prefer acidic soil down towards pH 6. NC State says moist, well-drained, acidic soils in dappled shade.
How much sun do azaleas need?
Clemson says azaleas prefer cool, partially shaded sites, such as the filtered shade of pine trees, and says azaleas in full sun are more susceptible to lace bugs. NC State says dappled shade.
When should you prune azaleas?
NC State says pruning, if desired, may be done after flowering. UF/IFAS says pruning can improve blooming and help azaleas develop into full, well-branched shrubs.
How do you fertilize azaleas?
Sparingly. Clemson says azaleas have low nutritional requirements compared to other shrubs and to have a specific reason before fertilizing. NC State says to avoid overwatering and over-fertilizing.
Do azaleas rebloom?
Some do. Clemson says reblooming types such as Encore offer blooms twice a year, in the spring and again in the fall. Other azaleas bloom from early spring to midsummer, depending on species.
Sources
- Azalea Care, Clemson Cooperative Extension, Home and Garden Information Center
- Azaleas, UF/IFAS Gardening Solutions
- Rhododendron (azalea), NC State Extension Plant Toolbox
- Azalea soil pH, University of Illinois Extension, Ask Extension
Hydrangea
Lavender